The present invention relates to a portable powered working machine such as a chain saw.
In general, a chain saw as an example of portable powered working machines has an internal combustion engine as the power source encased in a restricted space in a small casing. A carburetor and an air cleaner through which cleaned air is introduced to the carburetor are also mounted in the casing. The conventional chain saw, however, is generally difficult to handle and tends to rapid contamination of the air cleaner with the result that the engine performance is impaired undesirably. The contaminated air cleaner generates a large noise when air is sucked therethrough. At the same time, the mixture tends to be blown back from the carburetor to the air cleaner by the back pressure transmitted from the engine, undesirably accelerating the contamination of the air cleaner.
The chain saw has, in addition to the internal combustion engine as the power source, a fuel tank storing the fuel to be supplied to the engine and a lubricating oil tank storing a lubricating oil which lubricates the engine and the saw chain, the tanks also being encased in the casing. In known chain saws, the fuel tank and the lubricating oil tank are provided in the casing independently separately from each other, so that the number of parts is undesirably increased to make it difficult to realize a compact construction. In addition, much cost and time are required for the fabrication and assembly of the chain saw.
The power of a working machine such as a chain saw or a hedge cutter is controlled by manipulating a throttle lever of the internal combustion engine. In order to prevent any unintentional movement of the throttle lever, it is necessary to provide a throttle lock-out device. Conventionally, in this type of working machine, the throttle lever, the throttle lock-out device and a spring for biasing the throttle lock out device are formed as separate members and are assembled independently. In consequence, the number of parts is increased and much time and labor are required for the assembly of these parts.